Disabling the Security Check

If you are willing to accept the possible risk of linking to local content, you can override the security policy.

Note: If you are using the NoScript extension, the user_pref approach as described below does not work, NoScript overrules the checkloaduri configuration. Instead, it is possible to allow local links (file://) in your NoScript Options ("Advanced -> Trusted -> "Allow local links").

Site names must be listed as in the above example: the protocol (http://) followed by the domain name (www.example.com) followed by, if necessary, a port number (:8080). They should not include the final / or anything else from the path part of the URL.

Thunderbird 1.5, SeaMonkey 1.0 and newer

To enable opening file links you receive in e-mails, follow the example for Firefox 1.5, but with the user.js file in your Thunderbird profile. In the capability.policy.localfilelinks.sites entry, for POP3 enter mailbox://mail.example.com, or for mail on your system, simply mailbox://. For IMAP, use imap://mail.example.com. You may need to include your username or the port number. Something like (for IMAP):

If it's not working, turn on the (JavaScript) Error Console, click a link in an email, and look at the error message. It will tell you what path it's trying to access. Enter the first part of that path, up to and including the port number, in the capability.policy.localfilelinks.sites pref. Note that [1] implies that a rule with protocol mailbox: should allow mail in your pop3 mailbox to contain file: links, however it seems necessary to include in the rule the hierarchical symbol: mailbox://.

Path Syntax

You also need to use proper URI syntax for local file references. It is not proper to enter an operating-system-specific path, such as c:\subdir\file.ext without converting it to a URI, which in this case would be file:///c:/subdir/file.ext. In general, a file path is converted to a URI by adding the scheme identifier file:, then three forward slashes (representing an empty authority or host segment), then the path with all backslashes converted to forward slashes.